Showing papers on "Permeability (earth sciences) published in 2013"
TL;DR: This analysis provides the DRP community with a range of possible outcomes which can be expected depending on the solver and its setup, and falls within the ranges consistent with the relevant laboratory data.
453 citations
TL;DR: In this paper, the authors apply an algebraic multigrid method to solve for Stokes flow directly on binarized three-dimensional rock images, such as those obtained by micro-CT imaging.
Abstract: We apply an accurate numerical scheme to solve for Stokes flow directly on binarized three-dimensional rock images, such as those obtained by micro-CT imaging. The method imposes no-flow conditions exactly at the solid boundaries and employs an algebraic multigrid method to solve for the resultant set of linear equations. We compute the permeability of a range of consolidated and unconsolidated porous rocks; the results are comparable with those obtained using the lattice Boltzmann method and agree with experimental measurements on larger core samples. We show that the Kozeny–Carman equation can over-estimate permeability by a factor of 10 or more, particularly for the more heterogeneous systems studied. We study the existence and size of the representative elementary volume (REV) at lamina scale. We demonstrate that the REV for permeability is larger than for static properties—porosity and specific surface area—since it needs to account for the tortuosity and connectedness of the flow paths. For the carbonate samples, the REV appeared to be larger than the image size. We also study the anisotropy of permeability at the pore scale. We show that the permeability of sandpacks varies by less than 10 % in different directions. For sandstones, permeability changes by 25 % on average. However, the anisotropy of permeability in carbonates can be up to 50 %, indicating the existence of connected pores in one direction which are not connected in another.
347 citations
276 citations
TL;DR: In this paper, the effect of temperature on oil shale pyrolysis and the creation of pore volume during thermal treatment was investigated using three-dimensional X-ray micro tomography (XMT).
229 citations
TL;DR: In this paper, the U.S. Geological characterization was conducted which estimated total gas in-place and theoretical maximum CO2 storage capacity within the Marcellus Shale in the Eastern United States.
211 citations
TL;DR: In this paper, the authors presented a pore network model to determine the permeability of shale gas matrix, which is the first network model in 3D that combines pores with nanometer and micrometer sizes with different flow physics mechanisms on both scales.
Abstract: We present a pore network model to determine the permeability of shale gas matrix. Contrary to the conventional reservoirs, where permeability is only a function of topology and morphology of the pores, the permeability in shale depends on pressure as well. In addition to traditional viscous flow of Hagen–Poiseuille or Darcy type, we included slip flow and Knudsen diffusion in our network model to simulate gas flow in shale systems that contain pores on both micrometer and nanometer scales. This is the first network model in 3D that combines pores with nanometer and micrometer sizes with different flow physics mechanisms on both scales. Our results showed that estimated apparent permeability is significantly higher when the additional physical phenomena are considered, especially at lower pressures and in networks where nanopores dominate. We performed sensitivity analyses on three different network models with equal porosity; constant cross-section model (CCM), enlarged cross-section model (ECM) and shrunk length model (SLM). For the porous systems with variable pore sizes, the apparent permeability is highly dependent on the fraction of nanopores and the pores’ connectivity. The overall permeability in each model decreased as the fraction of nanopores increased.
205 citations
TL;DR: In this article, the deformation, strength and permeability evolution during triaxial compression of initially intact coals were measured by the constant pressure differential method, together with axial and volumetric strains for both water (H2O) and strongly adsorbing carbon dioxide (CO2) gas.
199 citations
TL;DR: In this article, the effect of the chemical nature of 12 types of nanoparticles on asphaltenes adsorption was analyzed and the delay or inhibition of deposition and precipitation of asphalte on porous media under flow conditions at reservoir pressure and temperature.
Abstract: The deposition of asphaltenes is one of the most difficult problems to overcome in oil production and processing. The presence of asphaltenes in crude oil, and consequently, the adsorption and deposition of asphaltenes on the rock surfaces, affects the rock properties, such as porosity, permeability, and wettability. This study aims at analyzing the effect of the chemical nature of 12 types of nanoparticles on asphaltenes adsorption; hence, the delay or inhibition of deposition and precipitation of asphaltenes on porous media under flow conditions at reservoir pressure and temperature were investigated. The adsorption equilibrium of asphaltenes onto nanoparticles was effectively achieved within relatively short times (approximately 2 min), which indicates the promising nature of adsorbents for delaying the agglomeration and inhibiting the precipitation and deposition of asphaltenes. The adsorption equilibrium of asphaltenes for the nanoparticles was determined using a batch method in the range 150–2000 mg...
175 citations
TL;DR: In this article, the authors numerically investigated the heat production potential from hot dry rock by water circulating through two horizontal wells, based on the geological data of well DP23-1 under the enhanced geothermal system (EGS) project at Desert Peak geothermal field.
146 citations
TL;DR: In this article, the authors improved the conventional relative permeability model for two-phase flow in porous media to describe the relative coal permeability for coal, and the effect of porosity change on relative coal is taken into account by introducing a residual phase saturation model and a shape factor as functions of permeability ratio.
136 citations
TL;DR: In this article, a reactive transport model was developed to simulate reaction of carbonates within a pore network for the high-pressure CO2-acidified conditions relevant to geological carbon sequestration.
Abstract: [1] A reactive transport model was developed to simulate reaction of carbonates within a pore network for the high-pressure CO2-acidified conditions relevant to geological carbon sequestration. The pore network was based on a synthetic oolithic dolostone. Simulation results produced insights that can inform continuum-scale models regarding reaction-induced changes in permeability and porosity. As expected, permeability increased extensively with dissolution caused by high concentrations of carbonic acid, but neither pH nor calcite saturation state alone was a good predictor of the effects, as may sometimes be the case. Complex temporal evolutions of interstitial brine chemistry and network structure led to the counterintuitive finding that a far-from-equilibrium solution produced less permeability change than a nearer-to-equilibrium solution at the same pH. This was explained by the pH buffering that increased carbonate ion concentration and inhibited further reaction. Simulations of different flow conditions produced a nonunique set of permeability-porosity relationships. Diffusive-dominated systems caused dissolution to be localized near the inlet, leading to substantial porosity change but relatively small permeability change. For the same extent of porosity change caused from advective transport, the domain changed uniformly, leading to a large permeability change. Regarding precipitation, permeability changes happen much slower compared to dissolution-induced changes and small amounts of precipitation, even if located only near the inlet, can lead to large changes in permeability. Exponent values for a power law that relates changes in permeability and porosity ranged from 2 to 10, but a value of 6 held constant when conditions led to uniform changes throughout the domain.
TL;DR: In this article, the authors couple the recently developed Liu and Harpalani sorption-induced strain model with various permeability models to predict coalbed methane (CBM) reservoirs during primary depletion, particularly in the San Juan Basin.
TL;DR: In this paper, the authors present the results of changing effective stresses, in terms of confining stresses and pore pressure, incorporating the role of coal swelling with time on the flow pattern of gaseous CO 2.
TL;DR: In this article, NMR experiments for samples treated at different temperatures (from 25°C to 375°C) were designed to study the variation of petrophysical properties of three Chinese coal cores with different ranks.
TL;DR: A theory of cross-coupled flow equations in unsaturated soils is necessary to predict electroosmotic flow with application to electroremediation and agriculture, the electroseismic and the seismoelectric effects to develop new geophysical methods to characterize the vadose zone, and the streaming current, which can be used to investigate remotely ground water flow in uns saturated conditions in the capillary water regime.
Abstract: A theory of cross-coupled flow equations in unsaturated soils is necessary to predict (1) electroosmotic flow with application to electroremediation and agriculture, (2) the electroseismic and the seismoelectric effects to develop new geophysical methods to characterize the vadose zone, and (3) the streaming current, which can be used to investigate remotely ground water flow in unsaturated conditions in the capillary water regime. To develop such a theory, the cross-coupled generalized Darcy and Ohm constitutive equations of transport are extended to unsaturated conditions. This model accounts for inertial effects and for the polarization of porous materials. Rather than using the zeta potential, like in conventional theories for the saturated case, the key parameter used here is the quasi-static volumetric charge density of the pore space, which can be directly computed from the quasi-static permeability. The apparent permeability entering Darcy's law is also frequency dependent with a critical relaxation time that is, in turn, dependent on saturation. A decrease of saturation increases the associated relaxation frequency. The final form of the equations couples the Maxwell equations and a simplified form of two-fluid phases Biot theory accounting for water saturation. A generalized expression of the Richard equation is derived, accounting for the effect of the vibration of the skeleton during the passage of seismic waves and the electrical field. A new expression is obtained for the effective stress tensor. The model is tested against experimental data regarding the saturation and frequency dependence of the streaming potential coupling coefficient. The model is also adapted for two-phase flow conditions and a numerical application is shown for water flooding of a nonaqueous phase liquid (NAPL, oil) contaminated aquifer. Seismoelectric conversions are mostly taking place at the NAPL (oil)/water encroachment front and can be therefore used to remotely track the position of this front. This is not the case for other geophysical methods.
12 Sep 2013
TL;DR: In this paper, the authors employed response surface methodology to optimize multiple horizontal well placement to maximize Net Present Value (NPV) with numerically modeling multistage hydraulic fractures in combination with economic analysis.
Abstract: Accurate placement of multiple horizontal wells drilled from the same well pad plays a critical role in the successful economical production from unconventional gas reservoirs. However, there are high cost and uncertainty due to many inestimable and uncertain parameters such as reservoir permeability, porosity, fracture spacing, fracture half-length, fracture conductivity, gas desorption, and well spacing. In this paper, we employ response surface methodology to optimize multiple horizontal well placement to maximize Net Present Value (NPV) with numerically modeling multistage hydraulic fractures in combination with economic analysis. This paper demonstrates the accuracy of numerical modeling of multistage hydraulic fractures for actual Barnett Shale production data by considering the gas desorption effect. Six uncertain parameters, such as permeability, porosity, fracture spacing, fracture half-length, fracture conductivity, and distance between two neighboring wells with a reasonable range based on Barnett Shale information, are used to fit a response surface of NPV as the objective function and to finally identify the optimum design under conditions of different gas prices based on NPV maximization. This integrated approach can contribute to obtaining the optimal drainage area around the wells by optimizing well placement and hydraulic fracturing treatment design and provide insight into hydraulic fracture interference between single well and neighboring wells.
TL;DR: In this article, the authors investigated the heat production potential from deep HDR (hot dry rock) at this site by water circulating through a novel single vertical fracture, where the injected water is assumed to sweep the fracture along the diagonal and the effect of high pressure and temperature on water density is taken into considerations.
TL;DR: The widely used coalbed methane flow model-triple porosity/dual permeability (TPDP) model indicates that coal pores can be divided into microtranspores, meso-macro-pores and fractures as discussed by the authors.
Abstract: The widely used coalbed methane (CBM) flow model-triple porosity/dual permeability (TPDP) model indicates that coal pores can be divided into micro-trans-pores, meso-macro-pores, and fractures, whi...
TL;DR: In this article, a thermal-hydro-mechanical (THM) coupled test apparatus was used to investigate the effect of stress, pore pressure and temperature on coal seams.
Abstract: Understanding the combined effect of stress, pore pressure and temperature on methane permeability is crucial to hazards detection and mitigation in deep coal mining. It is well known that mine temperature increases with mining depth and methane permeability decreases correspondingly. Methane extraction before coal mining lowers mine temperature and thus enhances permeability near working faces. On the other hand, coal seams can reach yield deformation more easily and even induce stress sharp drop or failure in higher temperature environments. The combined effect of stress, pore pressure and temperature might easily trigger a rapid enhancement of permeability near working faces or even coal and gas outbursts. Therefore, understanding this combined effect on methane permeability is a key issue to hazard detection and mitigation. So far, this combined effect has not been well understood in either experimental measurements or numerical simulations. This paper investigated the methane permeability of six gas-containing coal samples in a complete stress–strain process through our thermal-hydro-mechanical (THM) coupled test apparatus. In these tests, coal specimens were taken from the anthracite coals of Sihe colliery and Zhaozhuang colliery within the southeast Qinshui Basin in Shanxi province of China. A self-made ‘THM coupled with triaxial servo-controlled seepage apparatus for containing-gas coal’ was developed for these tests. The evolution of methane permeability in a complete stress–strain process was continuously measured under constant differential gas pressure, constant confining pressure and three constant temperatures of 30, 50 and \(70\,^{\circ }\hbox {C}\). These experimental results revealed that: (1) Higher temperature had lower compressive strength and lower limit strain, thus coal seams more easily failed. (2) The evolution of methane permeability of coal heavily depended on stress–strain stages. The permeability decreased with the increase of deviatoric stress at the initial compaction and elastic deformation stages, while it increased with the increase of deviatoric stress at the stages of yield deformation, stress sharp drop and residual stress. (3) Temperature effect on the permeability of coal varied with deformation stages, too. This effect was significant before yield deformation, where higher temperature caused lower permeability, but not important after yield deformation, at which the development of coal cracks became dominant. These observations and measurements are helpful for the design of hazards detection and mitigation measures during coal mining process.
TL;DR: In this article, the authors measured the change in permeability and chloride diffusivity with an increasing uniaxial load on ordinary concrete (OC) and high performance concrete (HPC).
TL;DR: In this article, a continuum coupled hydro-mechanical modeling approach is presented using a two-scale conceptual model representing realistic rock material containing micro-fractures, which combines a micro-crack-based continuous damage model within generalized Biot poroelasticity, in which the tensors of macroscopic elastic stiffness, Biot effective stress coefficient and of overall permeability are directly related to microcrack growth.
TL;DR: In this paper, the authors used effective confining pressure to simulate effective stress and found that high-rank coal permeability is susceptible to effective stress, and that coal samples' air permeability decreases exponentially with the rise of effective stress on the whole.
TL;DR: In this article, a naturally fractured coal specimen was chosen and the subcritical CO 2 flow was maintained by monitoring the injection pressures and ambient temperature; the variations in permeability under various scenarios were also investigated.
TL;DR: In this paper, the authors constructed a fit-for-purpose numerical simulator to examine various tight gas and shale gas systems and to identify and illustrate the various flow regimes which progressively occur over time.
10 Mar 2013
TL;DR: In this article, three transport models modified by the Darcy equation with apparent permeability are used to describe the combined gas transport mechanisms in ultra-tight porous media, the result shows that Knudsen diffusion has a great impact on the gas transport and Darcy's law cannot be used in a shale matrix with a pore diameter less than 1 μm.
08 Apr 2013
18 Mar 2013
TL;DR: Based on a detailed structural study performed on a reservoir surface analogue, a fracture permeability model for carbonate reservoirs is proposed in this paper, which involves four hierarchical systems, each one assumed to convey fluids exclusively to that of immediately higher order.